Re: [PATCH] ethernet/arc/arc_emac: Fix huge delays in large filecopies

From: Vineet Gupta
Date: Mon Sep 16 2013 - 01:44:09 EST


On 09/10/2013 11:57 AM, Vineet Gupta wrote:
> On 09/05/2013 11:55 PM, David Miller wrote:
>> From: Vineet Gupta <Vineet.Gupta1@xxxxxxxxxxxx>
>> Date: Wed, 4 Sep 2013 17:17:15 +0530
>>
>>> copying large files to a NFS mounted host was taking absurdly large
>>> time.
>>>
>>> Turns out that TX BD reclaim had a sublte bug.
>>>
>>> Loop starts off from @txbd_dirty cursor and stops when it hits a BD
>>> still in use by controller. However when it stops it needs to keep the
>>> cursor at that very BD to resume scanning in next iteration. However it
>>> was erroneously incrementing the cursor, causing the next scan(s) to
>>> fail too, unless the BD chain was completely drained out.
>>>
>>> [ARCLinux]$ ls -l -sh /disk/log.txt
>>> 17976 -rw-r--r-- 1 root root 17.5M Sep /disk/log.txt
>>>
>>> ========== Before =====================
>>> [ARCLinux]$ time cp /disk/log.txt /mnt/.
>>> real 31m 7.95s
>>> user 0m 0.00s
>>> sys 0m 0.10s
>>>
>>> ========== After =====================
>>> [ARCLinux]$ time cp /disk/log.txt /mnt/.
>>> real 0m 24.33s
>>> user 0m 0.00s
>>> sys 0m 0.19s
>>>
>>> Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
>>
>> Applied.
>>
>
> Hi Greg,
>
> This needs a stable backport (3.11).
> Mainline commit 27082ee1b92f4d41e78b85
>
> Thx,
> -Vineet

Hi Greg,

I didn't spot this one in your stable-queue for 3.11.
Please apply.

Thx,
Vineet



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